U.S. patent application number 16/075234 was filed with the patent office on 2019-02-07 for foldable cover assembly, method of manufacture, and device comprising the foldable cover assembly.
The applicant listed for this patent is SABIC Global Technologies, B.V.. Invention is credited to Jong-Min Choi, Jong Woo Lee, Seongnam Lee, Hao Zhou.
Application Number | 20190045038 16/075234 |
Document ID | / |
Family ID | 58228540 |
Filed Date | 2019-02-07 |
United States Patent
Application |
20190045038 |
Kind Code |
A1 |
Zhou; Hao ; et al. |
February 7, 2019 |
FOLDABLE COVER ASSEMBLY, METHOD OF MANUFACTURE, AND DEVICE
COMPRISING THE FOLDABLE COVER ASSEMBLY
Abstract
A foldable cover assembly includes a glass layer having a first
surface, a second surface opposite the first surface, a first
thickness at a first location and a second thickness at a second
location, wherein the second thickness is less than the first
thickness. The second thickness is further effective to provide
bendability to the glass layer. The foldable cover assembly further
includes an optically clear polymer film disposed on the first
surface of the glass layer. The polymer film includes a
thermoplastic polymer, a thermoset polymer, or a combination
comprising at least one of the foregoing, wherein a 100
micrometer-thick sample of the optically clear polymer film
transmits greater than 85% of visible light as determined according
to ASTM D1003-00. A method for the manufacture of the foldable
cover assembly is also described. The foldable cover assembly can
be useful for use with an electronic device.
Inventors: |
Zhou; Hao; (Mt. Vernon,
IN) ; Lee; Seongnam; (Seoul-si, KR) ; Choi;
Jong-Min; (Seongnam, KR) ; Lee; Jong Woo;
(Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SABIC Global Technologies, B.V. |
Bergen op Zoom |
|
NL |
|
|
Family ID: |
58228540 |
Appl. No.: |
16/075234 |
Filed: |
February 2, 2017 |
PCT Filed: |
February 2, 2017 |
PCT NO: |
PCT/US2017/016143 |
371 Date: |
August 3, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62291808 |
Feb 5, 2016 |
|
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|
62307654 |
Mar 14, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 2457/208 20130101;
B32B 27/36 20130101; H04M 1/0268 20130101; B32B 17/064 20130101;
B32B 2457/20 20130101; B32B 27/32 20130101; B32B 2307/412 20130101;
B32B 7/12 20130101 |
International
Class: |
H04M 1/02 20060101
H04M001/02; B32B 7/12 20060101 B32B007/12; B32B 17/06 20060101
B32B017/06; B32B 27/36 20060101 B32B027/36; B32B 27/32 20060101
B32B027/32 |
Claims
1. A foldable cover assembly (10), comprising a glass layer (1)
having a first surface (2), a second surface (3) opposite the first
surface (2), a first thickness (T.sub.1) at a first location (4)
and a second thickness (T.sub.2) at a second location (5), wherein
the second thickness is less than the first thickness, and is
effective to provide bendability to the glass layer; and an
optically clear polymer film (6) disposed on the first surface of
the glass layer, the polymer film comprising a thermoplastic
polymer, a thermoset polymer, or a combination comprising at least
one of the foregoing, wherein a 100 micrometer-thick sample of the
optically clear polymer film transmits greater than 85% of visible
light as determined according to ASTM D1003-00.
2. The foldable cover assembly of claim 1, wherein the cover
assembly transmits greater than 85% of visible light as determined
according to ASTM D1003-00.
3. The foldable cover assembly of claim 1, wherein the cover
assembly has a surface hardness of at least 7H as measured
according to ASTM 3363, a flexibility at the second location of 3R
or less as measured according to JIS K6902, or both.
4. The foldable cover assembly of claim 1, wherein the first
thickness of the glass layer is 50 micrometers to 1 millimeter.
5. The foldable cover assembly of claim 1, wherein the second
thickness of the glass layer is 10 to 750 micrometers.
6. The foldable cover assembly of claim 1, wherein the glass layer
comprises chemically strengthened glass, non-strengthened glass,
tempered glass, or optically transparent synthetic crystal.
7. The foldable cover assembly of claim 1, wherein the first
location is adjacent to the second location.
8. The foldable cover assembly of claim 1, wherein the second
thickness at a center point of the second location is less than the
second thickness at a periphery of the second location.
9. The foldable cover assembly of claim 1, wherein the polymer film
comprises a polyacetal, poly(C.sub.1-6 alkyl)acrylate,
polycarbonate, polyester, polyetherimide, polyimide, poly(C.sub.1-6
alkyl)methacrylate, polyolefin, polystyrene, polyurethane,
polyvinyl alcohol, polyvinyl ester, polyvinyl ether, polyvinyl
halide, polyvinyl nitrile, polyvinyl ketone, polyvinylidene
fluoride, a cyclic olefin copolymer, or a combination comprising at
least one of the foregoing thermoplastic polymers.
10. The foldable cover assembly of claim 1, wherein the polymer
film has a thickness of 1 micrometer to 20 millimeters.
11. The foldable cover assembly of claim 1, wherein the cover
assembly further comprises an optically clear adhesive layer
disposed between the first surface of the glass layer and the
polymer film, wherein a 50 micrometer-thick sample of the optically
clear adhesive transmits greater than 85% of visible light as
determined according to ASTM D1003-00.
12. The foldable cover assembly of claim 1, further comprising an
optically clear coating (7) disposed on at least a portion of the
second surface (3) of the second location (5) of the glass layer,
wherein the coating provides a difference in refractive index of
the second location and refractive of the first location that is
less than or equal to 0.05.
13. A method of manufacturing the foldable cover assembly of claim
1, the method comprising. applying the polymer film to the first
surface of the glass layer; contacting a masking layer with the
second surface of the glass layer, wherein the masking layer
comprises an aperture such that the first location of the glass
layer is covered by the masking layer and the second location of
the glass layer is exposed; etching at least a portion of the
exposed second location of the glass layer to provide the glass
layer having a first thickness at the first location and a second
thickness at the second location, wherein the second thickness is
less than the first thickness; and removing the masking layer from
the cover assembly.
14. The method of claim 13, further comprising applying an
optically clear coating (7) on at least a portion of the second
surface of the second location of the glass layer, wherein the
coating provides a difference in refractive index of the second
location and refractive of the first location that is less than or
equal to 0.05.
15. An electronic device comprising the foldable cover assembly of
claim 1.
16. The electronic device of claim 15, comprising the foldable
cover assembly disposed on a display of the electronic device.
17. The electronic device of claim 15, wherein the device is a
foldable device.
18. The electronic device of claim 15, wherein the device is a
cellular telephone, a smart telephone, a laptop computer, a
notebook computer, a tablet computer, a smart watch, an automobile
display device, or a medical device.
19. The electronic device of claim 15, wherein the cover assembly
is laminated onto the device, or molded onto the device, or adhered
onto the device via an adhesive layer, wherein a 50
micrometer-thick sample of the adhesive layer transmits greater
than 85% of visible light as determined according to ASTM
D1003-00.
20. An accessory for an electronic device comprising the foldable
cover assembly of claim 1.
Description
BACKGROUND
[0001] Electronic devices, including mobile electronic devices,
personal electronic devices, handheld electronic devices, and the
like typically include a display (e.g., a liquid crystal display).
Display covers protect the display of various electronic devices,
for example, from scratches, moisture, impact, and the like. Covers
including glass and polymeric materials have been developed.
Polymer-containing or "plastic" covers can suffer from poor scratch
resistance. Glass covers have also been developed, because glass
can be transparent and can be resilient to abrasion. However, while
glass typically provides enhanced scratch resistance compared to
plastic covers, glass can be brittle and susceptible to cracking
and failure (e.g., when impacted along an edge). Glass covers also
suffer from limitations relating to materials cost and ease of
manufacture.
[0002] Foldable electronic devices in particular require a cover
that is capable of folding with the device. A typical foldable
display is flexible and foldable, can be easily carried, and has a
large screen. A foldable display can be used in various devices
such as portable phones, portable multimedia players (PMP),
navigators, ultra-mobile personal computers (UMPC), electronic
books, electronic newspapers, televisions, or monitors. The display
industry generally prefers a 1 to 3 millimeter radius of folding
curvature. It would be further advantageous if a foldable cover for
use with a foldable display could withstand damage even after
200,000 folding cycles. As such, this requirement generally
precludes glass materials. Flexible films having inorganic/organic
hybrid coatings have also been explored. However, these can have
insufficient hardness, and thus fail to meet all requirements of a
foldable cover.
[0003] Accordingly, there remains a continuing need in the art for
an improved foldable cover for foldable electronic devices that can
overcome the above described technical limitations.
BRIEF DESCRIPTION
[0004] A foldable cover assembly comprises a glass layer having a
first surface, a second surface opposite the first surface, a first
thickness at a first location and a second thickness at a second
location, wherein the second thickness is less than the first
thickness, and is effective to provide bendability to the glass
layer; and an optically clear polymer film disposed on the first
surface of the glass layer, the polymer film comprising a
thermoplastic polymer, a thermoset polymer, or a combination
comprising at least one of the foregoing, wherein a 100
micrometer-thick sample of the optically clear polymer film
transmits greater than 85% of visible light as determined according
to ASTM D1003-00.
[0005] A method of manufacturing the foldable cover assembly
comprises applying the polymer film to the first surface of the
glass layer; contacting a masking layer with the second surface of
the glass layer, wherein the masking layer comprises an aperture
such that the first location of the glass layer is covered by the
masking layer and the second location of the glass layer is
exposed; etching at least a portion of the exposed second location
of the glass layer to provide the glass layer having a first
thickness at the first location and a second thickness at the
second location, wherein the second thickness is less than the
first thickness; and removing the masking layer from the cover
assembly.
[0006] An electronic device comprising the foldable cover assembly
is also described.
[0007] The above described and other features are exemplified by
the following figures and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The following figures are exemplary embodiments wherein the
like elements are numbered alike.
[0009] FIG. 1 shows a cross sectional view of a foldable cover
assembly.
[0010] FIG. 2 shows a cross sectional view of a foldable cover
assembly.
DETAILED DESCRIPTION
[0011] The present inventors have discovered a foldable cover
assembly for an electronic device having a glass/plastic laminated
structure which has been selectively etched or sintered to provide
a thin section, imparting flexibility to the cover. In addition to
exhibiting the desired flexibility and transparency for a foldable
cover assembly, the foldable cover assembly described herein can
further exhibit desirable surface hardness. Thus, the cover
assembly can be particularly useful as a front cover for an
electronic device (in particular, a foldable electronic device),
for example where the cover assembly is in contact with a foldable
display of the electronic device.
[0012] Accordingly, one aspect of the present disclosure is a
foldable cover assembly comprising a glass layer and an optically
clear polymer film. As used herein, the term "foldable" means that
the shape of the cover assembly is not fixed but can be transformed
from an initial shape into another shape. In other words, the term
"foldable" means that the cover assembly can be folded or bent
along one or more specific lines (a "fold-axis"). Additionally, the
term "foldable" also means that cover assembly can be curved, bent
or is rolled. The cover assembly can be as shown in FIG. 1. As
shown in FIG. 1, the foldable cover assembly (10) comprises a glass
layer (1) having a first surface (2) and a second surface (3)
opposite the first surface. The glass layer (1) further has a first
thickness (T.sub.1) at a first location (4) and a second thickness
(T2) at a second location (5). The foldable cover assembly further
comprises an optically clear polymer film (6) disposed on the first
surface (2) of the glass layer (1).
[0013] The glass layer has a first surface and a second surface
opposite the first surface. The glass layer can be, but is not
limited to, chemically strengthened glass (e.g., CORNING.TM.
GORILLA.TM. Glass commercially available from Corning Inc.,
XENSATION.TM. glass commercially available from Schott AG,
DRAGONTRAIL.TM. glass commercially available from Asahi Glass
Company, LTD, and CX-01 glass commercially available from Nippon
Electric Glass Company, LTD, and the like), non-strengthened glass
such as non-hardened glass including low sodium glass (e.g.,
CORNING.TM. WILLOW.TM. Glass commercially available from Corning
Inc. and OA-10G Glass-on-Roll glass commercially available from
Nippon Electric Glass Company, LTD, and the like), tempered glass,
or optically transparent synthetic crystal (also referred to as
sapphire glass, commercially available from GT Advanced
Technologies Inc.).
[0014] The glass layer further has a first thickness at a first
location and a second thickness at a second location. The second
thickness is less than the first thickness. The second thickness is
effective to provide bendability or flexibility to the glass layer.
The first location can be adjacent to the second location. In some
embodiments, the second location is preferably between a first and
second portion of the first location. In some embodiments, the
first thickness of the glass layer is 50 micrometers to 1
millimeter, preferably 50 micrometers to 0.7 millimeter, more
preferably 50 to 400 micrometers. In some embodiments, the second
thickness of the glass layer is 10 to 750 micrometers, preferably
10 micrometers to 500 micrometers, more preferably 10 to 300
micrometers. Without wishing to be bound by theory, it is believed
that the thickness of the second location (i.e., the second
thickness) facilitates the desirable foldability of the cover
assembly described herein.
[0015] In some embodiments, the second location of the glass layer
can have a variable thickness, provided that the thickness at any
given point in the second location is less than the first
thickness. In some embodiments, the second surface of the glass
layer at the second location can have a concave shape (for example,
as shown in FIG. 1). In some embodiments, the first surface of the
glass layer is substantially flat, and the concave shape of the
second location is formed from the second surface. In some
embodiments, the second thickness at a center point of the second
location is less than the second thickness at a periphery of the
second location (i.e., at or near a border of the first and second
locations).
[0016] In some embodiments, one or both surfaces of the glass layer
can be a textured surface, which can provide, for example,
anti-glare properties, anti-reflective properties, anti-microbial
properties, and the like, or a combination comprising at least one
of the foregoing.
[0017] In addition to the glass layer, the cover assembly further
includes an optically clear polymer film. The optically clear
polymer film is disposed on the first surface of the glass layer.
As used herein, the term "optically clear polymer film" means that
a 100 micrometer-thick sample of the optically clear polymer film
transmits greater than 85% of visible light as determined according
to ASTM D1003-00. In some embodiments, the optically clear polymer
film can have a thickness of 1 micrometer to 20 millimeters,
preferably 5 micrometers to 20 millimeters, more preferably 5
micrometers to 10 millimeters, even more preferably 5 micrometers
to 1 millimeter, even more preferably still 5 to 250 micrometers,
most preferably 5 to 100 micrometers.
[0018] The optically clear polymer film comprises a thermoplastic
polymer, a thermoset polymer, or a combination comprising at least
one of the foregoing. In some embodiments, the polymer film
comprises a thermoplastic polymer. As used herein, the term
"thermoplastic" refers to a material that is plastic or deformable,
melts to a liquid when heated, and freezes to a brittle, glassy
state when cooled sufficiently. Examples of thermoplastic polymers
that can be used include polyacetals (e.g., polyoxyethylene and
polyoxymethylene), poly(C.sub.1-6 alkyl)acrylates, polyacrylamides
(including unsubstituted and mono-N- and di-N-(C.sub.1-8
alkyl)acrylamides), polyamides (e.g., aliphatic polyamides,
polyphthalamides, and polyaramides), polyamideimides,
polyanhydrides, polyarylene ethers (e.g., polyphenylene ethers),
poly(arylene ketones) (e.g., polyetheretherketones (PEEK),
polyetherketoneketones (PEKK), polyetherketones (PEK), and the
like), polyarylene sulfides (e.g., polyphenylene sulfides (PPS)),
polyarylene sulfones (e.g., polyethersulfones (PES), polyphenylene
sulfones (PPS), and the like), polybenzothiazoles,
polybenzoxazoles, polybenzimidazoles, polycarbonates (including
homopolycarbonates and polycarbonate copolymers such as
polycarbonate-siloxanes, polycarbonate-esters, and
polycarbonate-ester-siloxanes), polyesters (e.g., polyethylene
terephthalates (PET), polybutylene terephthalates (PBT),
polyarylates, and polyester copolymers such as polyester-ethers),
polyetherimides (including copolymers such as
polyetherimide-siloxane copolymers), polyimides (including
copolymers such as polyimide-siloxane copolymers), poly(C.sub.1-6
alkyl)methacrylates, polymethacrylamides (including unsubstituted
and mono-N- and di-N-(C.sub.1-8 alkyl)acrylamides), cyclic olefin
polymers (including polynorbornenes and copolymers containing
norbornenyl units, for example copolymers of a cyclic polymer such
as norbornene and an acyclic olefin such as ethylene or propylene),
polyolefins (e.g., polyethylenes, polypropylenes, and their
halogenated derivatives (such as polytetrafluoroethylenes), and
their copolymers, for example ethylene-alpha-olefin copolymers,
polyoxadiazoles, polyoxymethylenes, polyphthalides, polysilazanes,
silicones (e.g., polydiorganosiloxanes), polystyrenes (including
copolymers such as acrylonitrile-butadiene-styrene (ABS) and methyl
methacrylate-butadiene-styrene (MBS)), polysulfides,
polysulfonamides, polysulfonates, polysulfones, polythioesters,
polytriazines, polyureas, polyurethanes, polyvinyl alcohols,
polyvinyl esters, polyvinyl ethers, polyvinyl halides, polyvinyl
nitriles, polyvinyl ketones, polyvinyl thioethers, polyvinylidene
fluorides, or the like, or a combination comprising at least one of
the foregoing thermoplastic polymers.
[0019] In some embodiments, the polymer film comprises a
polyacetal, a poly(C.sub.1-6 alkyl)acrylate, a polycarbonate, a
polyester, a polyetherimide, a polyimide, a poly(C.sub.1-6
alkyl)methacrylate, a polyolefin (including a cyclic olefin
copolymer), a polystyrene, a polyurethane, a polyvinyl alcohol, a
polyvinyl ester, a polyvinyl ether, a polyvinyl halide, a polyvinyl
nitrile, a polyvinyl ketone, a polyvinylidene fluoride, or a
combination comprising at least one of the foregoing thermoplastic
polymers. In some embodiments, the polymer film comprises a
polyimide, a polyetherimide, a polyester, a polyolefin, a
polycarbonate, a poly(C.sub.1-6 alkyl)acrylate, a poly(C.sub.1-6
alkyl)methacrylate, or a combination comprising at least one of the
foregoing. In some embodiments, the optically clear polymer film
comprises poly(methyl methacrylate), a polycarbonate, or a
combination comprising at least one of the foregoing.
[0020] In some embodiments, the optically clear polymer film can
include a polycarbonate. "Polycarbonate" as used herein means a
homopolymer or copolymer having repeating structural carbonate
units of formula (1)
##STR00001##
wherein at least 60 percent of the total number of R.sup.1 groups
are aromatic, or each R.sup.1 contains at least one C.sub.6-30
aromatic group. Polycarbonates and their methods of manufacture are
known in the art, being described, for example, in WO 2013/175448
A1, US 2014/0295363, and WO 2014/072923. Polycarbonates are
generally manufactured from bisphenol compounds such as
2,2-bis(4-hydroxyphenyl) propane ("bisphenol-A" or "BPA"),
3,3-bis(4-hydroxyphenyl) phthalimidine, (also known as N-phenyl
phenolphthalein bisphenol, "PPPBP", or
3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one),
1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane ("DMB"), or
1,1-bis(4-hydroxy-3-methylphenyl)-3,3,5-trimethylcyclohexane
("isophorone bisphenol"), or a combination comprising at least one
of the foregoing bisphenol compounds can also be used. In a
specific embodiment, the polycarbonate is a homopolymer derived
from BPA; a copolymer derived from BPA and another bisphenol or
dihydroxy aromatic compound such as resorcinol; or a copolymer
derived from BPA and optionally another bisphenol or
dihydroxyaromatic compound, and further comprising non-carbonate
units, for example aromatic ester units such as resorcinol
terephthalate or isophthalate, aromatic-aliphatic ester units based
on C.sub.6-20 aliphatic diacids, polysiloxane units such as
polydimethylsiloxane units, or a combination comprising at least
one of the foregoing.
[0021] In a specific embodiment, the polycarbonate is a linear
homopolymer containing bisphenol A carbonate units (BPA-PC),
commercially available under the trade name LEXAN from SABIC; or a
branched, cyanophenol end-capped bisphenol A homopolycarbonate
produced via interfacial polymerization, containing 3 mol %
1,1,1-tris(4-hydroxyphenyl)ethane (THPE) branching agent,
commercially available under the trade name LEXAN CFR from SABIC. A
combination of a linear polycarbonate and a branched polycarbonate
can be used. It is also possible to use a polycarbonate copolymer
or interpolymer rather than a homopolymer. Polycarbonate copolymers
can include copolycarbonates comprising two or more different types
of carbonate units, for example units derived from BPA and PPPBP
(commercially available under the trade name XHT from SABIC); BPA
and DMBPC (commercially available under the trade name DMX from
SABIC); or BPA and isophorone bisphenol (commercially available
under the trade name APEC from Bayer). The polycarbonate copolymers
can further comprise non-carbonate repeating units, for example
repeating ester units (polyester-carbonates), such as those
comprising resorcinol isophthalate and terephthalate units and
bisphenol A carbonate units, such as those commercially available
under the trade name LEXAN SLX from SABIC; bisphenol A carbonate
units and isophthalate-terephthalate-bisphenol A ester units, also
commonly referred to as poly(carbonate-ester)s (PCE) or
poly(phthalate-carbonate)s (PPC), depending on the relative ratio
of carbonate units and ester units; or bisphenol A carbonate units
and C.sub.6-12 dicarboxy ester units such as sebacic ester units
(commercially available under the trade name HFD from SABIC) Other
polycarbonate copolymers can comprise repeating siloxane units
(polycarbonate-siloxanes), for example those comprising bisphenol A
carbonate units and siloxane units (e.g., blocks containing 5 to
200 dimethylsiloxane units), such as those commercially available
under the trade name EXL from SABIC; or both ester units and
siloxane units (polycarbonate-ester-siloxanes), for example those
comprising bisphenol A carbonate units,
isophthalate-terephthalate-bisphenol A ester units, and siloxane
units (e.g., blocks containing 5 to 200 dimethylsiloxane units),
such as those commercially available under the trade name FST from
SABIC. Combinations of any of the above materials can be used.
[0022] Combinations of polycarbonates with other polymers can be
used, for example a combination (preferably an alloy) of bisphenol
A polycarbonate with an ester such as poly(butylene terephthalate)
or poly(ethylene terephthalate), each of which can be
semicrystalline or amorphous. Such combinations are commercially
available under the trade name XENOY and XYLEX from SABIC.
[0023] A specific copolycarbonate includes bisphenol A and bulky
bisphenol carbonate units, i.e., derived from bisphenols containing
at least 12 carbon atoms, for example 12 to 60 carbon atoms or 20
to 40 carbon atoms. These polycarbonates have high melting points,
good chemical resistance, and good scratch resistance. Examples of
such copolycarbonates include BPA-PPPBP copolymers such as LEXAN
XHT from SABIC), BPA-DMBPC copolymers such as LEXAN DMC from SABIC,
or a copolymer comprising bisphenol A carbonate units and
isophorone bisphenol carbonate units (commercially available under
the trade name APEC from Bayer) as described above.
[0024] The polycarbonates can have an intrinsic viscosity, as
determined in chloroform at 25.degree. C., of 0.3 to 1.5 deciliters
per gram (dl/gm), specifically 0.45 to 1.0 dl/gm. The
polycarbonates can have a weight average molecular weight of 10,000
to 200,000 Daltons, specifically 20,000 to 100,000 Daltons, as
measured by gel permeation chromatography (GPC), using a
crosslinked styrene-divinylbenzene column and calibrated to
polycarbonate references. GPC samples are prepared at a
concentration of 1 mg per ml, and are eluted at a flow rate of 1.5
ml per minute.
[0025] In some embodiments, the optically clear polymer film can
include a polyester as described above. Specific polyesters can
include PET, PBT, a glycol-modified poly(ethylene terephthalate),
poly(ethylene naphthalate) (PEN),
poly(1,4-cyclohexane-dimethanol-1,4-cyclohexane dicarboxylate)
(PCCD), poly(cyclohexanedimethylene terephthalate)-co-poly(ethylene
terephthalate), or a combination comprising at least one of the
foregoing polyesters.
[0026] In some embodiments, the optically clear polymer film can
include a cyclic olefin polymer, a polyolefin, or a combination
comprising at least one of the foregoing. Representative examples
of cyclic olefin polymers include polynorbornene and copolymers of
norbornene and ethylene or propylene. Representative examples of
polyolefins are polyethylene, polypropylene, polybutylene,
polymethylpentene (and co-polymers thereof), polynorbornene (and
co-polymers thereof), poly(1-butene), poly(3-methylbutene),
poly(4-methylpentene) and copolymers of ethylene with alpha-olefins
such as propylene, 1-butene, 1-hexene, 1-octene, 1-decene,
4-methyl-1-pentene and 1-octadecene. Representative combinations of
polyolefins are combinations containing polyethylene and
polypropylene, low-density polyethylene and high-density
polyethylene, and polyethylene and olefin copolymers containing
copolymerizable monomers, e.g., ethylene and acrylic acid
copolymers; ethyl and methyl acrylate copolymers; ethylene and
ethyl acrylate copolymers; ethylene and vinyl acetate copolymers,
ethylene, acrylic acid, and ethyl acrylate copolymers, and
ethylene, acrylic acid, and vinyl acetate copolymers. In some
embodiments, the thermoplastic polymer can include a polyolefin
elastomer.
[0027] Thermoset polymers are derived from thermosetting
prepolymers (resins) that can irreversibly harden and become
insoluble with polymerization or cure, which can be induced by heat
or exposure to radiation (e.g., ultraviolet light, visible light,
infrared light, or electron beam (e-beam) radiation). Thermoset
polymers include alkyds, bismaleimide polymers, bismaleimide
triazine polymers, cyanate ester polymers, benzocyclobutene
polymers, diallyl phthalate polymers, epoxies, hydroxymethylfuran
polymers, melamine-formaldehyde polymers, phenolics (including
phenol-formaldehyde polymers such as novolacs and resoles),
benzoxazines, polydienes such as polybutadienes (including
homopolymers and copolymers thereof, e.g.
poly(butadiene-isoprene)), polyisocyanates, polyureas,
polyurethanes, silicones, triallyl cyanurate polymers, triallyl
isocyanurate polymers, polyimides, certain silicones, and
copolymerizable prepolymers (e.g., prepolymers having ethylenic
unsaturation, such as unsaturated polyesters polyimides), or the
like. The prepolymers can be copolymerized or crosslinked with a
reactive monomer such as styrene, alpha-methylstyrene,
vinyltoluene, chlorostyrene, acrylic acid, (meth)acrylic acid, a
(C.sub.1-6 alkyl)acrylate, a (C.sub.1-6 alkyl) methacrylates,
acrylonitrile, vinyl acetate, allyl acetate, triallyl cyanurate,
triallyl isocyanurate, or acrylamide. The molecular weight of the
prepolymers can be 400 to 10,000 Daltons on average. A combination
of different thermosets can be used. Combinations comprising a
thermoplastic polymer and a thermoset polymer can also be used.
[0028] In some embodiments, one or both surfaces of the polymer
film can be a textured surface, which can provide, for example,
anti-glare properties, anti-reflective properties, anti-microbial
properties, and the like, or a combination comprising at least one
of the foregoing.
[0029] In some embodiments, the foldable cover assembly can
optionally further include an optically clear adhesive layer
disposed between the first surface of the glass layer and the
polymer film, wherein a 50 micrometer-thick sample of the optically
clear adhesive transmits greater than 85% of visible light as
determined according to ASTM D1003-00. In some embodiments, the
optically clear adhesive layer is in adhesive contact with the
entire first surface of the glass layer. When present, the
optically clear adhesive layer can have a thickness of 1 to 2000
micrometers, or 1 to 1000 micrometers, or 1 to 500 micrometers, or
1 to 100 micrometers, or 10 to 100 micrometers, or 10 to 50
micrometers, or 12.5 to 25 micrometers.
[0030] When present, the adhesive can include epoxy, acrylate,
amine, urethane, silicone, thermoplastic urethane, ethyl vinyl
acetate, hindered amine light stabilizer free ethyl vinyl acetate
(HALS free EVA), or a combination comprising at least one of the
foregoing. In an embodiment, the adhesive is a hindered amine light
stabilizer free ethyl vinyl acetate (HALS free EVA). In an
embodiment the adhesive is a thermoplastic urethane, or an ultra
violet light cured modified acrylate optical quality adhesive, or a
silicone pressure sensitive adhesive, or an acrylate pressure
sensitive adhesive. The adhesive can be applied using a process
such as roll lamination, roller coating, screen printing,
spreading, spray coating, spin coating, dip coating, and the like,
or a combination comprising at least one of the foregoing
techniques.
[0031] In some embodiments, the foldable cover assembly can
optionally further comprise a second optically clear adhesive
layer, preferably disposed on at least a portion of the polymer
film on a side opposite the glass layer. The second optically clear
adhesive layer can be the same or different from the optically
clear adhesive layer described above. In some embodiments, the
second optically clear adhesive layer functions to adhere the cover
assembly to an electronic device (e.g., a display of the electronic
device).
[0032] In some embodiments, the cover assembly can further include
one or more functional layers. A functional layer can be disposed
on at least a portion of the glass layer, the polymer film, or
both. In some embodiments, a functional layer is preferably
disposed on both sides of the glass layer, both sides of the
polymer layer, or both. The optional functional layer can include
an ultraviolet light protection layer, a touch sensing layer,
abrasion resistant layer, infrared absorbing layer, infrared
reflecting layer, hydrophobic layer, hydrophilic layer,
anti-fingerprint layer, anti-smudge layer, anti-glare layer,
anti-reflection layer, antimicrobial layer, conductive layer,
electromagnetic radiation shielding layer (e.g., an electromagnetic
interference shielding layer), anti-frost layer, anti-fog layer,
image forming layer (e.g., an ink layer), or a combination
including at least one of the foregoing. In some embodiments, the
functional layer can preferably include an anti-reflection layer,
an anti-glare layer, an antimicrobial layer, a conductive layer, an
anti-fingerprint layer, an anti-smudge layer, an anti-fog layer, or
a combination comprising at least one of the foregoing. In some
embodiments, the functional layer can further be textured. The
functional layer can be disposed in any form, e.g., a film,
coating, coextruded layer, deposited layer, molded layer, or the
like.
[0033] In some embodiments, the foldable cover assembly can
optionally further comprise an optically clear coating, as shown in
FIG. 2. When present, the optically clear coating can be disposed
on at least a portion of the second surface of the second location
of the glass layer, wherein the coating provides a difference in
refractive index of the second location and refractive of the first
location that is less than or equal to 0.05. A 50 micrometer-thick
sample of the optically clear coating transmits greater than 85% of
visible light as determined according to ASTM D1003-00. When
present, the optically clear coating can have a thickness of 1 to
1000 micrometers, or 1 to 500 micrometers, or 1 to 100 micrometers,
or 10 to 100 micrometers, or 10 to 50 micrometers, or 12.5 to 25
micrometers. When present, the optically clear coating can comprise
an optically clear thermoplastic polymer film, wherein the
optically clear thermoplastic polymer can be as described
above.
[0034] The foldable cover assembly can have one or more of the
following properties.
[0035] The foldable cover assembly can preferably be a transparent
foldable cover assembly, wherein the cover assembly transmits
greater than 85% of visible light as determined according to ASTM
D1003-00.
[0036] In some embodiments, the foldable cover assembly can have a
surface hardness of at least 7H. Without wishing to be bound by
theory, it is believed that the cover assembly will not crack
easily when impacted at such a hardness. Surface hardness can be
determined by measuring pencil hardness according to ASTM D3363.
Pencil hardness is a measure of the hardness of a material on a
scale ranging from 9H (hardest) to 9B (softest). In general, the
pencil hardness scale is 9H (hardest), 8H, 7H, 6H, 5H, 4H, 3H, 2H,
H, F, HB (medium), B, 2B, 3B, 4B, 5B, 6B, 7B, 8B, and 9B (softest),
for example, at 700 g. Thus, in some embodiments, the foldable
cover assembly can have a hardness that is 7H, 8H, or 9H.
[0037] As mentioned above, the glass layer has a first thickness
and a second thickness, wherein the second thickness is effective
to provide bendability to the glass layer. Accordingly, in some
embodiments, the foldable cover assembly is bendable, preferably
the cover assembly has a flexibility of 3R or less as measured
according to JIS K6902. In some embodiments, the cover assembly can
advantageously exhibit a flexibility of 3R or less while
maintaining the surface hardness.
[0038] The foldable cover assembly can be manufactured by applying
the polymer film to the first surface of the glass layer. The
polymer film can be prepared using any method for preparing a
polymer film that is generally known. For example, the polymer film
can be prepared by extrusion, solution casting, melt blowing, 3D
printing, mono- or bi-axial stretching, and the like. In some
embodiments, the polymer film is prepared by extrusion, solution
casting, or melt blowing. Optionally, the polymer film can be
applied to the glass layer via an adhesive layer, as discussed
above. When present, the adhesive layer can first be applied to the
at least a portion of the first surface of the glass layer, and the
polymer film can subsequently be applied thereto. The adhesive can
be applied using any suitable process including, but not limited
to, roll lamination, roller coating, screen printing, spreading,
spray coating, spin coating, dip coating, and the like, or a
combination comprising at least one of the foregoing
techniques.
[0039] The method of manufacturing the foldable cover assembly
further comprises contacting a masking layer with the second
surface of the glass layer (i.e., on a side opposite the polymer
film). The masking layer comprises an aperture such that a portion
of the second surface of the glass layer remains exposed, and the
remaining portion of the second surface of the glass layer is
covered. Preferably, the masking layer includes an aperture such
that the first location of the glass layer is covered by the
masking layer and the second location of the glass layer is
exposed.
[0040] The masking layer can include materials such as films or
inks that can be coated on the second surface of the glass layer,
for example, by lamination or screen printing processes. Exemplary
masking materials can include, but are not limited to an inorganic
oxide (e.g., silicon dioxide), an inorganic nitride (e.g., silicon
nitride), a cured resin, a wax coating, and the like, or a
combination comprising at least one of the foregoing. After
contacting the masking layer with the second surface of the glass
layer, the at least a portion of the exposed second location of the
glass layer is etched to provide a glass layer having a first
thickness at the first location and a second thickness at the
second location, wherein the second thickness is less than the
first thickness. As discussed above, the second thickness is
effective to provide bendability (i.e., flexibility) to the glass
layer. The etching can be using any suitable etching process
including, chemical etching (e.g., using aqueous solutions
comprising one or more water-soluble inorganic fluoride compounds
having utility for the dissolution of silicate glasses including,
for example, HF, sodium fluoride, potassium fluoride, ammonium
fluoride, sodium bifluoride, potassium bifluoride, ammonium
bifluoride, and or a combination comprising at least one of the
foregoing)., laser etching, or a combination comprising at least
one of the foregoing etching processes. One of ordinary skill in
the art would readily understand what type of masking layer would
be suitable for a particular etching process selected for the
selective etching of the second surface of the glass layer. The
masked, glass layer can be subjected to the desired etching process
for an appropriate time to achieve the desired second thickness of
the glass layer. After the selective etching has been completed
(including washing off the etching solution with deionized water,
for example), the masking layer can be removed. For example, the
masking layer can be peeled or otherwise stripped using a suitable
stripper solution depending on the particular masking layer
composition employed in the selective etching process.
[0041] In some embodiments, when an optically clear coating is
present on at least a portion of the second surface of the second
location of the glass layer, as described above and as shown in
FIG. 2, the method can further comprise applying the optically
clear coating to the desired portion of the second surface of the
second location of the glass layer, preferably applying the coating
to the etched portion of the second surface of the glass layer. The
applying can be by, for example, roll lamination, roller coating,
screen printing, spreading, spray coating, spin coating, dip
coating, and the like, or a combination comprising at least one of
the foregoing techniques. In some embodiments, a film of the
optically clear coating can be prepared and subsequently laminated
to the desired portion of the cover assembly.
[0042] The foldable cover assemblies of the present disclosure can
be useful for a wide variety of applications including consumer
electronics. Accordingly, an electronic device comprising the cover
assembly represents another aspect of the present disclosure. In
some embodiments, the foldable cover assembly can be disposed on a
display of an electronic device (e.g., as a screen protector for
the display of the device), preferably a foldable electronic
device. The displays are preferably foldable displays. In some
embodiments, the display can be a touch screen display. Examples of
electronic devices that can be utilized with the cover assembly
include but are not limited to, a cellular telephone, a smart
telephone, a laptop computer, a notebook computer, a tablet
computer, an automotive display (e.g., an automotive interior
center console display), a medical device, a smart window, public
information displays, a wearable electronic device (e.g., smart
watch, activity tracker, health tracker, health monitoring devices,
and the like). In some embodiments, the foldable cover assembly can
be useful as an accessory for an electronic device. For example, a
cover or case for an electronic device (e.g., a mobile electronic
device) can include the foldable cover assembly. In some
embodiments, a cover or case comprising the foldable cover assembly
can be a foldable cover or case for use with a foldable electronic
device. In some embodiments, the foldable cover assembly can
further serve as a barrier layer for oxygen and moisture, such that
no additional barrier layer is required (i.e., to protect the
electronic device from oxygen and moisture).
[0043] In some embodiments, the foldable cover assembly is
laminated onto the electronic or lighting device, molded onto the
electronic or lighting device, or adhered onto the electronic or
lighting device via an adhesive layer. When an adhesive layer is
used, a 50 micrometer thick sample of the adhesive layer transmits
greater than 85% of visible light as determined according to ASTM
D1003-00.
[0044] The foldable cover assembly described herein provides a
lightweight cover assembly for a foldable electronic device, where
bendability of the cover assembly is required. Advantageously, the
foldable cover assembly exhibits transmission of greater than 85%
of visible light, as determined according to ASTM D1003-00, as well
as the desired combination of surface hardness and flexibility.
Thus, a significant improvement in foldable cover assemblies for
electronic devices is provided by the present disclosure.
[0045] This disclosure further encompasses the following
non-limiting embodiments.
[0046] Embodiment 1: A foldable cover assembly (10), comprising a
glass layer (1) having a first surface (2), a second surface (3)
opposite the first surface (2), a first thickness (T.sub.1) at a
first location (4) and a second thickness (T2) at a second location
(5), wherein the second thickness is less than the first thickness,
and is effective to provide bendability to the glass layer; and an
optically clear polymer film (6) disposed on the first surface of
the glass layer, the polymer film comprising a thermoplastic
polymer, a thermoset polymer, or a combination comprising at least
one of the foregoing, wherein a 100 micrometer-thick sample of the
optically clear polymer film transmits greater than 85% of visible
light as determined according to ASTM D1003-00.
[0047] Embodiment 2: The foldable cover assembly of embodiment 1,
wherein the cover assembly transmits greater than 85% of visible
light as determined according to ASTM D1003-00.
[0048] Embodiment 3: The foldable cover assembly of embodiment 1 or
2, wherein the cover assembly has a surface hardness of at least 7H
as measured according to ASTM 3363, a flexibility at the second
location of 3R or less as measured according to JIS K6902, or
both.
[0049] Embodiment 4: The foldable cover assembly of any one or more
of embodiments 1 to 3, wherein the first thickness of the glass
layer is 50 micrometers to 1 millimeter, preferably 50 micrometers
to 0.7 millimeter, more preferably 50 to 400 micrometers.
[0050] Embodiment 5: The foldable cover assembly of any one or more
of embodiments 1 to 4, wherein the second thickness of the glass
layer is 10 to 750 micrometers, preferably 10 micrometers to 500
micrometers, more preferably 10 to 300 micrometers.
[0051] Embodiment 6: The foldable cover assembly of any one or more
of embodiments 1 to 5, wherein the glass layer comprises chemically
strengthened glass, non-strengthened glass, tempered glass, or
optically transparent synthetic crystal.
[0052] Embodiment 7: The foldable cover assembly of any one or more
of embodiments 1 to 6, wherein the first location is adjacent to
the second location, preferably wherein the second location is
between a first and second portion of the first location.
[0053] Embodiment 8: The foldable cover assembly of any one or more
of embodiments 1 to 7, wherein the second thickness at a center
point of the second location is less than the second thickness at a
periphery of the second location.
[0054] Embodiment 9: The foldable cover assembly of any one or more
of embodiments 1 to 8, wherein the polymer film comprises a
polyacetal, poly(C.sub.1-6 alkyl)acrylate, polycarbonate,
polyester, polyetherimide, polyimide, poly(C.sub.1-6
alkyl)methacrylate, polyolefin, polystyrene, polyurethane,
polyvinyl alcohol, polyvinyl ester, polyvinyl ether, polyvinyl
halide, polyvinyl nitrile, polyvinyl ketone, polyvinylidene
fluoride, a cyclic olefin copolymer, or a combination comprising at
least one of the foregoing thermoplastic polymers, preferably
wherein the polymer film comprises poly(ethylene terephthalate),
poly(ethylene naphthalate),
poly(1,4-cyclohexane-dimethanol-1,4-cyclohexane dicarboxylate),
poly(cyclohexanedimethylene terephthalate)-co-poly(ethylene
terephthalate), polyethylene, polypropylene, a bisphenol A
polycarbonate homopolymer, a bisphenol A polycarbonate copolymer,
poly(4,4'-oxydiphenylene-pyromellitimide), polyvinylidene fluoride,
polyvinyl fluoride, poly(methyl methacrylate), polystyrene,
polyoxymethylene, poly(ethylene-vinyl acetate, polymethylpentane,
or a combination comprising at least one of the foregoing.
[0055] Embodiment 10: The foldable cover assembly of any one or
more of embodiments 1 to 9, wherein the polymer film has a
thickness of 1 micrometer to 20 millimeters, preferably 5
micrometers to 20 millimeters, more preferably 5 micrometers to 10
millimeters, even more preferably 5 micrometers to 1 millimeter,
even more preferably still 5 to 250 micrometers, most preferably 5
to 100 micrometers.
[0056] Embodiment 11: The foldable cover assembly of any one or
more of embodiments 1 to 10, wherein the cover assembly further
comprises an optically clear adhesive layer disposed between the
first surface of the glass layer and the polymer film, wherein a 50
micrometer-thick sample of the optically clear adhesive transmits
greater than 85% of visible light as determined according to ASTM
D1003-00.
[0057] Embodiment 12: The foldable cover assembly of any one or
more of embodiments 1 to 11, further comprising an optically clear
coating (7) disposed on at least a portion of the second surface
(3) of the second location (5) of the glass layer, wherein the
coating provides a difference in refractive index of the second
location and refractive of the first location that is less than or
equal to 0.05.
[0058] Embodiment 13: A method of manufacturing the foldable cover
assembly of any one or more of embodiments 1 to 12, the method
comprising: applying the polymer film to the first surface of the
glass layer; contacting a masking layer with the second surface of
the glass layer, wherein the masking layer comprises an aperture
such that the first location of the glass layer is covered by the
masking layer and the second location of the glass layer is
exposed; etching at least a portion of the exposed second location
of the glass layer to provide the glass layer having a first
thickness at the first location and a second thickness at the
second location, wherein the second thickness is less than the
first thickness; and removing the masking layer from the cover
assembly.
[0059] Embodiment 14: The method of embodiment 13, further
comprising applying an optically clear coating (7) on at least a
portion of the second surface of the second location of the glass
layer, wherein the coating provides a difference in refractive
index of the second location and refractive of the first location
that is less than or equal to 0.05.
[0060] Embodiment 15: An electronic device comprising the foldable
cover assembly of any one or more of embodiments 1 to 12.
[0061] Embodiment 16: The electronic device of embodiment 15,
comprising the foldable cover assembly disposed on a display of the
electronic device.
[0062] Embodiment 17: The electronic device of embodiment 15 or 16,
wherein the device is a foldable device.
[0063] Embodiment 18: The electronic device of any one or more of
embodiments 15 to 17, wherein the device is a cellular telephone, a
smart telephone, a laptop computer, a notebook computer, a tablet
computer, a smart watch, an automobile display device, or a medical
device.
[0064] Embodiment 19: The electronic device of any one or more of
embodiments 15 to 18, wherein the display is a touch screen
display.
[0065] Embodiment 20: The electronic device of any one or more of
embodiments 15 to 19, wherein the cover assembly is laminated onto
the device, or molded onto the device, or adhered onto the device
via an adhesive layer, wherein a 50 micrometer-thick sample of the
adhesive layer transmits greater than 85% of visible light as
determined according to ASTM D1003-00.
[0066] Embodiment 21: An accessory for an electronic device
comprising the foldable cover assembly of any one or more of
embodiments 1 to 12, preferably wherein the accessory is a cover or
case for a mobile electronic device.
[0067] The assemblies, methods, and devices can alternatively
comprise, consist of, or consist essentially of, any appropriate
components or steps herein disclosed. The assemblies, methods, and
devices can additionally, or alternatively, be formulated so as to
be devoid, or substantially free, of any steps, components,
materials, ingredients, adjuvants, or species that are otherwise
not necessary to the achievement of the function or objectives of
the assemblies, methods, and devices.
[0068] All ranges disclosed herein are inclusive of the endpoints,
and the endpoints are independently combinable with each other.
"Combinations" is inclusive of blends, mixtures, alloys, reaction
products, and the like. The terms "first," "second," and the like,
do not denote any order, quantity, or importance, but rather are
used to distinguish one element from another. The terms "a" and
"an" and "the" do not denote a limitation of quantity, and are to
be construed to cover both the singular and the plural, unless
otherwise indicated herein or clearly contradicted by context. "Or"
means "and/or" unless clearly stated otherwise. Reference
throughout the specification to "some embodiments," "an
embodiment," and so forth, means that a particular element
described in connection with the embodiment is included in at least
one embodiment described herein, and may or may not be present in
other embodiments. In addition, it is to be understood that the
described elements may be combined in any suitable manner in the
various embodiments.
[0069] Unless defined otherwise, technical and scientific terms
used herein have the same meaning as is commonly understood by one
of skill in the art to which this application belongs. All cited
patents, patent applications, and other references are incorporated
herein by reference in their entirety. However, if a term in the
present application contradicts or conflicts with a term in the
incorporated reference, the term from the present application takes
precedence over the conflicting term from the incorporated
reference.
[0070] The term "alkyl" means a branched or straight chain,
unsaturated aliphatic hydrocarbon group, e.g., methyl, ethyl,
n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n-pentyl, s-pentyl,
and n- and s-hexyl. "Alkenyl" means a straight or branched chain,
monovalent hydrocarbon group having at least one carbon-carbon
double bond (e.g., ethenyl (--HC.dbd.CH.sub.2)). "Alkoxy" means an
alkyl group that is linked via an oxygen (i.e., alkyl-O--), for
example methoxy, ethoxy, and sec-butyloxy groups. "Alkylene" means
a straight or branched chain, saturated, divalent aliphatic
hydrocarbon group (e.g., methylene (--CH.sub.2--) or, propylene
(--(CH.sub.2).sub.3--)). "Cycloalkylene" means a divalent cyclic
alkylene group, --C.sub.nH.sub.2n-x, wherein x is the number of
hydrogens replaced by cyclization(s). "Cycloalkenyl" means a
monovalent group having one or more rings and one or more
carbon-carbon double bonds in the ring, wherein all ring members
are carbon (e.g., cyclopentyl and cyclohexyl). "Aryl" means an
aromatic hydrocarbon group containing the specified number of
carbon atoms, such as phenyl, tropone, indanyl, or naphthyl. The
prefix "halo" means a group or compound including one more of a
fluoro, chloro, bromo, or iodo substituent. A combination of
different halo groups (e.g., bromo and fluoro), or only chloro
groups can be present. The prefix "hetero" means that the compound
or group includes at least one ring member that is a heteroatom
(e.g., 1, 2, or 3 heteroatom(s)), wherein the heteroatom(s) is each
independently N, O, S, Si, or P. "Substituted" means that the
compound or group is substituted with at least one (e.g., 1, 2, 3,
or 4) substituents that can each independently be a C.sub.1-9
alkoxy, a C.sub.1-9 haloalkoxy, a nitro (--NO.sub.2), a cyano
(--CN), a C.sub.1-6 alkyl sulfonyl (--S(.dbd.O).sub.2-alkyl), a
C.sub.6-12 aryl sulfonyl (--S(.dbd.O).sub.2-aryl) a thiol (--SH), a
thiocyano (--SCN), a tosyl (CH.sub.3C.sub.6H.sub.4SO.sub.2--), a
C.sub.3-12 cycloalkyl, a C.sub.2-12 alkenyl, a C.sub.5-12
cycloalkenyl, a C.sub.6-12 aryl, a C.sub.7-13 arylalkylene, a
C.sub.4-12 heterocycloalkyl, and a C.sub.3-12 heteroaryl instead of
hydrogen, provided that the substituted atom's normal valence is
not exceeded. The number of carbon atoms indicated in a group is
exclusive of any substituents. For example --CH.sub.2CH.sub.2CN is
a C.sub.2 alkyl group substituted with a nitrile.
[0071] While particular embodiments have been described,
alternatives, modifications, variations, improvements, and
substantial equivalents that are or may be presently unforeseen may
arise to applicants or others skilled in the art. Accordingly, the
appended claims as filed and as they may be amended are intended to
embrace all such alternatives, modifications variations,
improvements, and substantial equivalents.
* * * * *